Author Topic: Roll Your Windows Down  (Read 686 times)

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Offline 2483R

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Roll Your Windows Down
« on: Tuesday,August 16, 2016, 02:52:25 PM »
Introduction

I was working on my Europa TC driver’s side door one day somewhere around 1986. I had removed the interior door panel and began to remove the window electric motor/arm. Once I removed the motor/arm the window glass promptly fell to the inside bottom of the door, while still in the frame channel.

At the time, my Europa windows were as per factory built, lowering to point about 3 inches above the top of door, (see picture 1: a photo of my car around 1986). I have read Lotus designed the car this way because the curvature of the glass/door would not allow the windows to be lowered any more.

But I was able to move the window glass up and down the window frame freely by hand, from sitting on the inside bottom of the door to fully closed, without any binding or contact with the curvature of the door. Curious, I decided to take a closer look and ultimately modified both doors to allow the windows to roll down completely. See picture 2 for how my windows look when down since 1986.

The purpose of this article is to explain ‘how to’ modify your car to roll your windows  down. Due to the hand made nature of the cars I cannot say this mod will work on all cars. I do not own an S2 and the doors do have a different P/N than TCs, so I cannot say it will work on S2s either. But it does work on my car, and there should be many other cars were it will work as well.

Description

A drawing of the Europa door with window, window frame, and electric motor is in picture 3, which was taken from the workshop manual. The window frame is built from channel with a U-shaped cross section. It has a brace welded near the bottom, and 2 L-shaped pieces tack welded on each side of the frame near the center. The L-shaped pieces provide a lip at the window opening at the top of the door.

Inspection revealed the tack weld from the forward channel and the outside L-shaped piece was broken (thank you Lotus quality control). A gap of roughly 1/8 inch existed between the forward channel and the outside L-shaped piece.

At the inside top of the door is a bracket, one end of the bracket is riveted to the fiberglass door and the other end is welded to the U channel. The weld from the U channel to the bracket had also failed.

Driver Side

Thinking any movement of metal could lead to fatigue/failure I decided to stop any frame movement. I wedged a small strip of hard black rubber between forward channel and the outside L-shaped piece (picture 4). This also pushes the forward channel inside the door back from the door curvature slightly.

I tested by moving the window up and down by hand, without the electric motor/arm installed. No binding in the frame or window contact with the door could be seen. To see contact is actually not easy due to the construction of the door. A mirror is essential. One way to test is to make a long strip of cardboard, try sliding it between the inner door surface and the glass. If you can slid it, you have a gap at least as thick as your cardboard. You don’t need a lot of clearance, but you do need clearance.

Satisfied that the window is moving up/down freely by hand, the next step is modify the electric motor/arm to allow this additional movement. The motors are actually GM units which Lotus limited their movement by tack welding washers on the arm gear. To increase the arm movement remove a section of the washer, I used a hacksaw (picture 5). Do this in small increments, if the arm hits the bottom of the door it could puncture the door. Remove enough washer material so that arm stops just above the bottom of the door. You can use your long strip of cardboard to test for clearance between the arm and the bottom of the door.

If you cut too much from the motor arm washers there is some slop in the door bolt holes which hold the motor. The slop does provide some adjustment as you can move the motor a small amount.

Test again with the electric motor/arm back in the door, move the window in small increments. Each time you turn the motor off, check the arm for any binding or contact. The arm slides in its own channel attached to the bottom of the glass (picture 3) and can bind there. If the arm is binding then the arm may have to be re-bent.

Passenger Side

Happy with what I had done on the driver side window I then applied the same procedure to the passenger side. Taking the electric motor/arm out I  tried moving the window glass up/down the frame by hand. The window glass contacted the inner surface of the door, just beyond the factory built point were you could normally lower the door.

Inspection revealed the tack weld from the forward channel and the outside L-shaped piece was intact. The bracket from the channel to the door was also intact.

Thinking I had little to loose I used a small chisel to break the tack weld at the outside L-shaped piece. As before, I wedged a small strip of hard black rubber between forward channel and the outside L-shaped piece (see picture 4).

This increased the movement of the window but I still was unable to have window completely down without contact with the inner door surface. I wedged hard rubber blocks between the forward and rear channel and the inner door surface (picture 6). This moves the channels away from the inner door surface. Use a rubber block large enough to spread the load on the door over a wide area and avoid dimpling the surface of the door.

The thickness of this hard rubber block is variable. You need just enough thickness to allow the window to clear the inner door surface, but don’t make them so thick that the channel breaks or buckles.

As before, test everything before cutting washers on the motor/arm. Place the motor back in the door and test everything again.

Summary

It is possible to have the window glass roll down to the bottom of the door. This will require moving or bending of the window channel. As the clearances are tight, a small amount of moving or bending will make a big difference.

This is an easy mod to do, it costs nothing save for your time. It increases cabin ventilation and makes the car much nicer to drive. There is some risk involved as it is possible to break the glass, buckle your window frame, or damage the door. But if you are careful, go slowly, test thoroughly, the risk is nominal.

In 30 years of driving the car like this I have yet to encounter any problems or issues with this mod.

Ron Dawson













Offline BDA

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Re: Roll Your Windows Down
« Reply #1 on: Tuesday,August 16, 2016, 04:51:15 PM »
Very interesting! Thanks!